Add scheduler overview documentation

This patch series updates the scheduler documentation to add more topics
wrt to scheduler overview. New sections are added to provide a brief
overview of the kernel structs used by the scheduler, scheduler invocation,
context switch and Capacity Aware Scheduling. Previous version of
the patch was reviewed at:
Link: https://lore.kernel.org/lkml/20200513134338.19688-2-John....

version 5:
 -Fix description error on CAS

version 4:
 -Added section on Capacity-Aware Scheduling
 -Reworded CFS recently added features.
 -Removed vruntime description from scheduler structs
 -Added description of idle and stopper sched classses

version 3:
 -Fix spelling, spacing and typo errors.

version 2:
- Remove :c:func: directive as it was redundant
- Limit document width (line symbol count) to 75
- Replace dot file with ASCII art
- Describe prepare_task_switch(), ASID use, 
  kernel/user transtion, MIPS FPU affinity correctly
- Add missing references to files
- Removed internal APIs from scheduler API reference
- Described rq struct member as kernel-doc comments
- Replaced CFS history with CFS current status
- Added documentation for sched_class fields
- Refined explanation of context swtich functionality
- Replace CFS history with recent changes
- Added kernel-doc comments for struct rq

John Mathew (3):
  docs: scheduler: Restructure scheduler documentation.
  docs: scheduler: Add scheduler overview documentation
  docs: scheduler: Add introduction to scheduler context-switch

 Documentation/scheduler/arch-specific.rst     |  14 +
 Documentation/scheduler/cfs-overview.rst      | 102 ++++++
 Documentation/scheduler/context-switching.rst | 125 ++++++++
 Documentation/scheduler/index.rst             |  33 +-
 .../scheduler/mips-context-switch.rst         |  89 ++++++
 Documentation/scheduler/overview.rst          | 293 ++++++++++++++++++
 Documentation/scheduler/sched-cas.rst         |  92 ++++++
 .../scheduler/sched-data-structs.rst          | 182 +++++++++++
 Documentation/scheduler/sched-debugging.rst   |  14 +
 Documentation/scheduler/sched-features.rst    |  21 ++
 Documentation/scheduler/scheduler-api.rst     |  31 ++
 .../scheduler/x86-context-switch.rst          |  65 ++++
 kernel/sched/core.c                           |  28 +-
 kernel/sched/sched.h                          | 169 +++++++++-
 14 files changed, 1238 insertions(+), 20 deletions(-)
 create mode 100644 Documentation/scheduler/arch-specific.rst
 create mode 100644 Documentation/scheduler/cfs-overview.rst
 create mode 100644 Documentation/scheduler/context-switching.rst
 create mode 100644 Documentation/scheduler/mips-context-switch.rst
 create mode 100644 Documentation/scheduler/overview.rst
 create mode 100644 Documentation/scheduler/sched-cas.rst
 create mode 100644 Documentation/scheduler/sched-data-structs.rst
 create mode 100644 Documentation/scheduler/sched-debugging.rst
 create mode 100644 Documentation/scheduler/sched-features.rst
 create mode 100644 Documentation/scheduler/scheduler-api.rst
 create mode 100644 Documentation/scheduler/x86-context-switch.rst

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2.17.1